Submission #1094117

#	Time	Username	Problem	Language	Result	Execution time	Memory
1094117		ASN49K	Climbers (RMI18_climbers)	C++14	100 / 100	153 ms	196180 KiB

climbers

#include <bits/stdc++.h>
using namespace std;
using i64=long long;
#define UNUSED -1
#define all(x) x.begin(),x.end()
#define pb push_back
#define int long long
const int mod=1e9+7,inf=1e9+1;
const i64 INF=1e18;
struct node
{
    int nod1,nod2;
    long long cost;

    bool operator <(const node& b) const
    {
        return cost>b.cost;
    }
};

bool between(int a,int b,int c)
{
    return (a<=b && b<=c) || (a>=b && b>=c);
}
void modify_h(vector<int>&h)
{
    vector<int>sol;
    for(auto &c:h)
    {
        while(sol.size()>=2 && between(sol[sol.size()-2],sol.back(),c))
        {
            sol.pop_back();
        }
        sol.push_back(c);
    }
    h=sol;
}
main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin>>n;
    vector<int>h(n);
    for(auto &c:h)
    {
        cin>>c;
    }
    modify_h(h);
    n=(int)h.size();
    priority_queue<node>q;
    vector<vector<i64>>dist(n,vector<i64>(n-1,INF));
    dist[0][n-2]=0;
    q.push({0,n-2,0});
    auto add=[&](int x,int y,i64 cost)
    {
        if(dist[x][y]>cost)
        {
            dist[x][y]=cost;
            q.push({x,y,cost});
        }
    };
    while(q.size())
    {
        auto then=q.top();
        q.pop();
        int nod1=then.nod1,nod2=then.nod2;
        if(then.cost != dist[nod1][nod2])
        {
            continue;
        }
        if(nod1==nod2 || nod1==nod2+1)
        {
            cout<<then.cost;
            return 0;
        }

        //we move to nod1+1
        if(nod1+1<n && (between(h[nod1],h[nod1+1],h[nod2]) || between(h[nod1],h[nod1+1],h[nod2+1])))
        {
            add(nod1+1,nod2,then.cost+abs(h[nod1+1]-h[nod1]));
        }
        if(nod1-1>=0 && between(h[nod1],h[nod1-1],h[nod2]) || between(h[nod1],h[nod1-1],h[nod2+1]))
        {
            add(nod1-1,nod2,then.cost+abs(h[nod1-1]-h[nod1]));
        }

        if(nod1+1<n && between(h[nod1],h[nod2],h[nod1+1]))
        {
            add(nod2,nod1,then.cost+abs(h[nod2]-h[nod1]));
        }
        if(nod1+1<n && between(h[nod1],h[nod2+1],h[nod1+1]))
        {
            add(nod2+1,nod1,then.cost+abs(h[nod2+1]-h[nod1]));
        }

        if(nod1>0 && between(h[nod1],h[nod2],h[nod1-1]))
        {
            add(nod2,nod1-1,then.cost+abs(h[nod2]-h[nod1]));
        }
        if(nod1>0 && between(h[nod1],h[nod2+1],h[nod1-1]))
        {
            add(nod2+1,nod1-1,then.cost+abs(h[nod2+1]-h[nod1]));
        }
    }
    cout<<"NO";
}

Compilation message (stderr)

climbers.cpp:38:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   38 | main()
      | ^~~~
climbers.cpp: In function 'int main()':
climbers.cpp:83:22: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   83 |         if(nod1-1>=0 && between(h[nod1],h[nod1-1],h[nod2]) || between(h[nod1],h[nod1-1],h[nod2+1]))
      |            ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 50 / 50